Image Forming Apparatus Fixing Device Warm-Up Control
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Solution Overview
Problem
Existing image forming apparatuses with fixing devices face challenges in reducing warm-up time and power consumption while maintaining temperature control, particularly when using a pressure belt as one of the pressing members, leading to issues like prolonged warm-up times, durability concerns, and image failures due to temperature unevenness.
Innovation Solution
The apparatus incorporates a separating mechanism and temperature detecting units to control the heating and pressing members independently, allowing them to reach target temperatures efficiently and reducing the need for complex power distribution, thereby minimizing warm-up time and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the diameters of the rollers are increased to increase the fixing nip width, then the fixing nip width is improved, but the heat capacity of the rollers increases and warm-up time increases
Solution Approach 1:
The patent introduces a belt stretching mechanism that allows the endless belt to be dynamically adjusted in length and tension. This enables the fixing nip width to be varied without changing roller diameters, resolving the contradiction between maintaining a large fixing nip width and reducing warm-up time of the rollers.
Solution Approach 2:
The patent changes the parameter of fixing nip width control from roller diameter to belt contact width. By adjusting the belt stretching members and belt tension, the effective fixing nip width can be modified independently of the roller dimensions, thus avoiding increased heat capacity while maintaining the required fixing width.
2Power
If maximum electric power is supplied to the upper heater during warm-up, then the warm-up speed is improved, but the warm-up time is prolonged due to heat loss to the lower pressing member
Solution Approach 1:
The patent applies preliminary action by separating the upper and lower pressing members before warm-up. This prevents heat loss from the upper heater to the lower pressing member during the warm-up phase, allowing efficient heat accumulation in the upper pressing member without the time penalty of heat dissipation.
Solution Approach 2:
The patent segments the heating process into distinct phases: warm-up with members separated, and fixing operation with members contacted. This segmentation allows independent optimization of each phase, enabling rapid warm-up without heat loss while maintaining effective fixing when members are contacted.
3Device complexity
If the pressing members are kept in contact during warm-up, then temperature control is simplified, but temperature unevenness occurs and image failures result
Solution Approach 1:
The patent performs preliminary separation of pressing members during warm-up to prevent temperature unevenness. This preliminary action ensures uniform temperature distribution before the fixing operation begins, eliminating image failures while the control complexity remains manageable through automated sequencing.
Solution Approach 2:
The patent implements periodic action by alternating between separated state (during warm-up) and contacted state (during fixing operation). This periodic switching optimizes both temperature uniformity and fixing effectiveness, preventing image failures while maintaining reliable operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables faster warm-up and standby times with simpler control, reduces temperature unevenness, and prevents image failures by ensuring both pressing members are brought to their target temperatures before forming the nip section, enhancing the overall efficiency and reliability of the image forming process.
Implementation Method 1
a heating member and a pressing member that form a nip section to heat and press the image formed on the recording medium
Implementation Method 2
a first temperature detecting unit that detects temperature of the pressing member
Data Source
AI summary
In an image forming apparatus including a fixing device that uses a pressure belt as at least one of two pressing members, a warm-up time and time for shifting to a standby state are reduced with simple control without increasing power consumption. The two pressing members are brought into a press-contact state by a contacting/separating mechanism and only heating means on the upper side is turned on. When the temperature of the upper pressing member increases to temperature near a target temperature corresponding thereto, the pressing members are driven to rotate. When it is detected by temperature detecting means on the lower side that the temperature of the lower pressing member increases to temperature near a target temperature corresponding thereto, the two pressing members are brought into a separated state by the contacting/separating mechanism.